1. Field of the Invention
The present invention relates to the field of integrated circuits. More particularly, the invention provides a heat sink for use with stacks of integrated circuits.
2. Description of the Related Art
As computer manufacturers have attempted to build more powerful machines, the use of chip stacks in modern computing applications has become increasingly desirable. The term xe2x80x98chipsxe2x80x99 used with the present invention is intended to include any packaged integrated circuit device including processing devices e.g. microprocessors etc., memory devices e.g. DRAMS, SRAMS, etc., and the like. In essence, a chip stack comprises multiple integrated circuit packages which are stacked together (back-to-front or back-to-back). The chip stacks may be oriented either in face up position or in a side-to-side orientation with chip edges down.
There are a number of advantages to the chip stack configuration over conventional single chip mounting arrangements. In particular, the chip stacks provide a more compact circuit arrangement for computers and other high speed electronic systems.
In addition, chip stacks particularly allow for more efficient use of space on circuit boards. The stack takes advantage of relatively less valuable space above the circuit board, while at the same time leaving a small footprint on a circuit board or card, thereby increasing the space available for other components or chip stacks.
While there are numerous advantages to a stacked chip configuration, there are also associated problems. Specifically, larger and larger chip stacks create unique cooling problems. Because the chip stacks contain multiple chips, they generate more heat per unit volume, requiring greater heat dissipation, while at the same time providing significantly smaller surface areas which may be used as a heat sink. In view of this problem, the general response in the industry to the need for cooling chip-stacks has been to immerse the entire chip-stack in liquid or to operate at greatly reduced power levels. This is often an unwelcome solution because of technical concerns and also because of customer and user preferences.
The present invention is generally directed at providing a relatively low cost heat sink for dissipating heat generated within chip stacks (sometimes referred to as xe2x80x98chip cubesxe2x80x99, although a cubic structure is not necessary). The invention provides a heat absorbing surface between at least a first and second chip within a chip stack which is connected to a heat dissipating surface located outside the stack. According to a preferred embodiment, the heat sink includes one or more heat absorbing sections for respective insertion between chips within one or more chip stacks; a heat transfer section for transferring heat away from the absorbing sections; and a heat dissipating section for commonly dissipating heat transferred from the heat absorbing sections.
These and other features and advantages of the invention will become more readily apparent from the following detailed description of preferred embodiments of the invention which are provided in connection with the accompanying drawings.